The portable operating system interface POSIX, standardized in the international standards ISO/IEC/IEEE 9945, includes a number of specific application environment profiles (AEPs) for open multi-tasking systems. Among these in particular are the environment profiles, defined in accordance with IEEE 1003.13-2003, for portable, real-time-capable and embedded applications.
Not standardized, however, is the arbitration logic—falling first and foremost within the area of responsibility of the operating system kernel—which controls the quasi-parallel, thus, at least seemingly concurrent execution of the applications. Corresponding control programs are known in operating-system theory as schedulers. In the area of real-time-capable operating systems considered, to that end, what are referred to as interrupting or preemptive schedulers are used.
In this context, generic-type preemptive schedulers of POSIX-compliant operating systems follow the strategy of priority scheduling, according to which each process is assigned a priority, and in each case, the executable process having the highest priority is brought to execution.
U.S. Patent Appl. Ser. No. 2008/0235701 A1 describes the possible use of a newer class of algorithms known as an adaptive partition scheduler. According to that, a symmetrical multiprocessor system includes a plurality of processing units and corresponding instances of an adaptive partition scheduler. Based on a comparison between merit-function values of the adaptive partitions, each instance of the adaptive partition scheduler assigns the respective processing unit selectively to threads of several adaptive partitions. The merit function for a specific partition among the adaptive partitions may depend on whether the adaptive partition possesses a runtime allocation on the processing unit in question. Additionally or alternatively, the merit function for a specific partition associated with an instance of the adaptive partition scheduler may depend on whether the adaptive partition has a global runtime allocation on the symmetrical multiprocessor system.